One of the more common afflictions to affect aging eyes are cataracts, which cause gradually deteriorating vision. Advances in ophthalmic surgery allow many cataracts to be removed and vision restored.
Treating cataracts typically involves the removal of the clouded natural lens and replacement with an artificial lens. Removal of the lens requires an incision or tunnel to be made in and/or adjacent to the cornea and a phaco-emulsifier needle or tip to be inserted into the eye. The phaco-emulsifier tip vibrates ultrasonically to break up or liquefy the lens. The emulsified lens is removed from the eye by aspiration, and the artificial lens is then inserted.
Modern phacoemulsifiers and aspirators have long but narrow cylindrical tips with coaxial passages. Aspiration typically is through a central passage of circular cross section. Simultaneously, irrigation is through an annular passage encircling the aspiration passage. In the typical arrangement, the central, circular aspiration passage extends axially of the phacoemulsifier handpiece for connection to an external vacuum source. The irrigation liquid is conveyed from an external source through a conduit that enters the distal end of the handpiece, near the tip. Both external sources are connected to the handpiece by flexible tubes, so that the handpiece can be manipulated during the phacoemulsifying and cleansing procedures.